(1202 – 1261)
Mathematical sciences owe a lot to this dinosaur, who ranks amongst the most gifted mathematicians of all time. His extraordinary works on the Chinese Remainder Theorem has remained influential for well-over 500 years. After the theorem was adopted in Europe, some problems whose solutions eluded even Euler became solvable. Qin’s exploration of algebra extended to quartic equations (which are fourth order polynomials), and to quintic equations (which are algebraically unsolvable in terms of finite additions, subtractions, multiplications, divisions, and root extractions: as proven by the later works of Niels Abel and Évariste Galois). Qin Jiushao was also an accomplished astronomer whose narratives revealed how solstice and other related astronomical data could be derived from traditional lunisolar calendars. Apart from incorporating the zero-symbol into written Chinese mathematics, Qin is credited with finding sums of arithmetic series. His techniques and methodologies bolstered various branches of algebra. Evidence abound that he dissected the much-talked-about Ruffini-Horner method more than 500 years before Paolo Ruffini and William Horner rediscovered it in the 19th century Europe. Although most of his publications were lost, those that survived indicated that he also worked extensively on surveying and engineering.